<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>let</title>
</head>

<body>
  <script>
    //声明变量
    let a;
    let b, c, d;
    let e = 100;
    let f = 521,
      g = 'iloveyou',
      h = [];

    //1.变量不能重复声明
    let star = '罗志祥';
    let star = '小猪';
    
    //2.块级作用域 全局，函数,eval,if,else, while, for
    {
      var girl = '周扬青';
      // let girl = '周扬青';
    }

    console.log(girl);

    //3.let不存在变量提升
    // console.log(song);
    let song = '恋爱达人';

    //4.不影响作用链
    {
      let school = '尚硅谷';
      function fn() {
        console.log(school);
      }

      fn();  //尚硅谷
    }
  </script>
</body>

</html>